The shoring of bridges and trestles, including railroad bridges and trestles, is a necessary and vital activity that must be undertaken to ensure safe and continuous traffic during the construction or repair of the bridge, particularly where existing bridge bents are substandard. Conventionally, shoring a bridge included framing a new timber bent to replace or augment the existing substandard bent. Shoring a bridge with a new timber bent required driving new piles adjacent to the piles of the substandard bent and placing a new timber cap over the new piles. In addition, timber shims were necessarily installed between the new timber cap and the stringers of the bridge's superstructure to ensure a tight fit to carry the traffic loads. Such conventional shoring of a bridge was a costly undertaking because: a) the new timber piles were driven between the rails and under the existing bridge, requiring extensive work on the superstructure of the existing bridge, b) most of the material used for the new bent was timber, and once cut, the timber could not be used again except in cases where timber of the cut length or shorter were required. The new timber bent was also constructed of creosote treated timbers resulting in pollution of any waterway over which the bridge was constructed.
In addition, a skilled carpenter had to be on hand to ensure the dimensions and fit-up were correct. Also, new Federal Railway Administration (FRA) guidelines require that all temporary falsework, shoring, and brace frames (including new timber bents) have to be designed by a professional engineer. Consequently, the design costs, required to design a new timber frame, mount quickly.